For example, in an automobile and the like, there is used a clamp attaching a pipe (pipe material) for an air-conditioner or for a fuel to a vehicle body. The clamp is formed by assembling a clamp main body holding the pipe, and a clip locked in the attachment object through an elastic member. For example, in the clip, there is provided a T-shaped rib, and long holes are formed in the clamp main body and the elastic member. The long hole of the clamp main body and the long hole of the elastic member are overlapped, and the T-shaped rib of the clip is inserted into the long holes and is rotated after being inserted, so that the clip and the clamp are fixed through the elastic member as a retainer of the rib of the clip.